| 摘要 |
PCT No. PCT/GB91/00065 Sec. 371 Date Aug. 6, 1992 Sec. 102(e) Date Aug. 6, 1992 PCT Filed Jan. 17, 1991 PCT Pub. No. WO91/10806 PCT Pub. Date Jul. 25, 1991.A centralizer for well casings is disclosed which, in one aspect has spring strips which are normally bowed to centralize the casing, but which are held in a collapsed disposition against the casing while the casing is positioned in a borehole. The holding force may be provided by a band and/or an arrangement of struts which are released when the casing is positioned. An additional energizing device may be provided to increase the bowing of the spring strips for more certain engagement with the surrounding borehole.
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